1. Field of the Invention
The invention relates to the field of thermometers, and more particularly to the field of non-mercury non-electronic clinical thermometers.
2. Description of the Related Art
For use in a health care field, a wide variety of materials and methods are available for detecting temperature and temperature changes. The most common example of a temperature indicating device is the mercury bulb thermometer. Bulb thermometers rely on the simple principle that the volume of a liquid expands upon heating and diminishes when cooled. Mercury bulb thermometers have become undesirable since mercury is highly toxic. In fact, many countries are actively banning or limiting the use of mercury and mercury thermometers.
Electronic thermometers generally offer a great number of advantages over conventional glass and mercury thermometers. Among the advantages of electronic thermometers are a digital temperature display to eliminate temperature reading errors; and with proper circuit design and calibration, higher accuracy and resolution is possible with accurate measurement and display of tenths of a degree Fahrenheit being easily attainable.
However, the above electronic thermometers are expensive since they require circuitry and/or processor chip. Furthermore, such electronic thermometers typically use a chemical battery as a power supply. In general, the electronic thermometers are idle for a long time since patients only use the electronic thermometers while they are sick or feel uncomfortable. Thus such electronic thermometers employing a chemical battery as a power supply are not environmentally friendly.